This invention pertains to well apparatus, and more particularly to connectors for joining marine risers to subsea wellheads.
When preparing to produce fluids from an offshore well that has been completed with a subsea wellhead, a marine riser pipe is lowered from the surface platform and connected to the wellhead to provide guidance and protection for internally run production casing. In some instances the connection must be accomplished remotely and automatically, i.e., without the assistance of a diver, and the connector also must be capable of being rigidly yet releasably locked to the wellhead with diver assist. Such a connector must have an outside diameter small enough to pass through the platform jacket guides, an ability to adjust for any angular and/or horizontal misalignment with the wellhead, and an inside diameter large enough to pass successive tie-back strings. These requirements seriously restrict the type and design of connector suitable for this purpose, and though many connectors are known none possess all of the required features.